1. Field of Invention
The invention refers to a device for calibrating geometric measurements, orienting and positioning of surgical tools in space.
2. Description of Related Art
Such devices are suitable for the calibration of geometric measurements, especially of the diameter, position and/or orientation of surgical tools in space. The calibration of the position and orientation is above all needed for surgical tools employed in computer-assisted surgery, where the position and orientation of various surgical tools is measured, during an operation, while using a surgical navigation system including a position detecting device. Such a navigation system merely allows determining the position of a marking indicator applied to the tool or a machine comprising the tool, for instance a drilling machine. An intra-operative calibration is for instance indispensable for drilling processes where the drill, if inserted into a drilling machine in-situ, is inserted into a position with respect to the drilling machine and the marking indicators which is previously unknown.
A device of this kind is known from the EP-A 0 904 735 MESSNER. This known calibrating device also allows, apart from determining the position of the tip of a tool, measuring the diameter of the tool by using two jaws than can be shifted to each other in a linear manner. Before the measurement, the jaws must be shifted relative to each other so as to precisely contact the mantle surface of the surgical tool along their entire longitudinal axis parallel to the surgical tool. The disadvantage of this known device is that measuring errors may occur if the jaws cannot make proper contact over their entire length.